1. Field of the Invention
The invention relates in general to a method for receiving a station signal and a receiver for receiving the same, and more particularly to a method for receiving a station signal and a receiver for receiving the same capable of automatically scanning a station frequency.
2. Description of the Related Art
Conventional TV systems adopting analog modulating method include USA-dominated NTSC system, EU-dominated PAL system and USSR-dominated SECAM system. As for audio modulation, the carrier frequency modulation is normally adopted to transmit a radio frequency signal, and is also referred as frequency modulation (FM).
Generally, the FM radio also adopts frequency modulation in transmitting a radio frequency signal, and the bandwidth approximately ranges between 76˜108 MHz (the bandwidth ranges between 87˜108 MHz in USA/Taiwan, and ranges between 76˜90 MHz in Japan). The bandwidth is divided in an interval of 200 KHz to create a channel. The transmitter modulates the frequency of the radio frequency signal in a channel and transmits the frequency modulation signal to a receiver.
Some of the conventional TVs or frequency modulation receivers possess an auto scanning function. That is, a mixed frequency of a receiver is increased or decreased, such that a determination as to whether the frequency is locked by a phase lock loop (PLL) is made, and the existence of a station signal is detected by the squelch detector. However, the reliability of the result of detection obtained by auto scanning mentioned above is changed according to the temperature and the time of the working environment. Besides, it is difficult to apply auto scanning to the working environment of multiple communication systems.